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Niels Lohmann
354d5fa723
Add JSON_HEDLEY_WARN_UNUSED_RESULT to the unambiguous, const, side-effect-free observer functions whose return value is the entire purpose of the call: - dump() - type(), type_name() - all is_* predicates (is_primitive, is_structured, is_null, is_boolean, is_number, is_number_integer, is_number_unsigned, is_number_float, is_object, is_array, is_string, is_binary, is_discarded) - empty(), size(), max_size() - count(...) (both overloads) and contains(...) (all overloads, including the deprecated json_pointer<BasicJsonType> overload) This mirrors the direction the standard library has taken with [[nodiscard]] on the analogous std::vector/std::map members, and catches real bugs such as `j.empty();` (meant `j.clear();`) or `j.contains(k);` with the result thrown away. Deliberately out of scope (left for a separate, later policy decision, per the issue): at(), value(), get*(), flatten(), unflatten(), patch(), merge_patch(), begin()/end(), comparison operators, erase(), and emplace(). Compiling the full test suite (tests/src/unit-*.cpp) with -Wunused-result -Werror uncovered one real hit: a regression test in unit-regression2.cpp called dump() purely to check it does not throw, discarding the result. Fixed by explicitly casting to void, since the call is intentionally result-less there. Fixes #5410 Signed-off-by: Niels Lohmann <mail@nlohmann.me>